The Low-Carb Craze

To low-carb or not to low-carb? It’s the dieting question that in recent times has divided nutritionists, health professionals, and a personal trainer or two.

The low-carb craze reached its apotheosis in recent years with the keto diet, which took over the blogosphere and social media and blew into mainstream consciousness. But in the past 12 months it has experienced pushback from experts due to its side effects; some experts say it’s bad for your workout performance and potentially even dangerous.

Of course, the debate over low-carb diets is so lively because up until now we’ve lacked the proper research to truly make a call on how good that diet is -- but things might be about to change.

A New Low-Carb Study, Explained

Researchers from Boston Children’s Hospital, Harvard Medical School and other universities have produced compelling new evidence of the benefits of going low-carb. Their study, published in the journal BMJ, is being touted by Vox as “arguably one of the most rigorous diet studies ever done.”

The $12 million study recruited 234 people and involved two steps. First, they were simply set a goal of losing 12 percent of their body weight over nine to ten weeks. This initial task gets directly at what we’re told over and over again about dieting: losing weight is one thing; keeping it off is another.

164 of the subjects achieved the target weight and entered the second part of the study. They were then randomly assigned either a high carb, moderate carb or low carb diet, and had their meals and snacks carefully dished out to them for 20 weeks.

After the five-month period was up, the differences in results were telling. People on the low-carb diet had burned 200 extra calories a day and the moderates 100 calories a day. Those on the high-carb diet didn’t chew through any extra calories.

“This feeding study, as the longest and largest to date, provides support for the carbohydrate-insulin model and makes a credible case that all calories are not metabolically alike,” one of the study authors, Harvard’s Ludwig, is quoted in the Vox story as saying. “These findings raise the possibility that a focus on carbohydrate restriction may work better for long-term weight loss maintenance than calorie restriction.”

The Carbohydrate-Insulin Hypothesis

So what’s going on here? Basically, the study looks like it’s confirmed one of the core hypotheses of the low-carb diet -- the carbohydrate-insulin model.

The carbohydrate-insulin model suggests that a carb-heavy diet leads to weight gain because carbohydrates drive up insulin in the body and cause it to hold on to fat, hampering its ability to burn calories.

To keep off the weight, you need to reduce your carbohydrate intake and replace it with fat calories. Insulin levels go down, which then encourages calorie burn, and in turn melts away at the fat. This, in essence, is what happened to the low-carb group in the new study.

Before You Ditch That Bowl Of Pasta

The research has a couple of caveats.

First, the findings may still not be applicable to most people. Why? Because it has proven extremely hard in the past to get people to follow a diet that’s not being fed to them.

The second issue is maybe more problematic, and involves a measurement technique, doubly labelled water, commonly used with “free-living” subjects (that is, people who aren’t in a metabolic chamber). The way it was implemented in this study delivered some potentially erroneous results -- a point the Vox story goes into some detail to explain.

In short, don’t switch up what you eat just yet. More evidence is needed. In the meantime the best diet is, as always, the one you can stick to.